1. Field of the Invention
The present invention relates to the structure of a fuel cell stack.
2. Description of the Related Art
A fuel cell, which directly converts chemical energy to electric energy by utilizing electrochemical reaction of reaction gases including an anode gas such as hydrogen and a cathode gas such as oxygen, has been well known.
Japanese Unexamined Patent Application Publication No. 2006-92924 discloses a solid polymer electrolyte fuel cell stack including a plurality of single cells. Each of the single cells includes a membrane electrode assembly (hereinafter referred to as “MEA”) and separators disposed on both sides of the MEA. The MEA has an anode electrode and a cathode electrode sandwiching an electrolyte membrane therebetween. In the outer periphery of the fuel cell stack, insulating resin members are formed so that the stacked single cells can be joined to each other and insulation from the outside can be ensured.
However, in the fuel cell stack described in Japanese Unexamined Patent Application Publication No. 2006-92924, the plurality of single cells and the resin members are integrally formed. Therefore, when the electrolyte membranes of the MEAs swell and the fuel cell stack expands in the direction in which the single cells are stacked (hereinafter referred to as “the stacking direction”), the resin members cannot follow displacement of the fuel cell stack, or in other words, displacements between the plurality of MEAs. This may cause resin members to crack. If the resin members crack, water vapor generated in the MEAs may leak out from the inside of the fuel cell stack to the outside, a liquid junction may be generated, and insulation performance of the fuel cell stack may deteriorate.